Electrical Engineering Stack Exchange
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Questions tagged [common-gate]

One of the three basic FET amplifier topologies. The FET's source terminal is the input, the drain is the output, and the gate is connected to ground (or "common", hence the name). The analogous BJT circuit is the common base. Use this tag along with the "mosfet" and "transistors" tags for questions about common gate circuits.

One of the three basic FET amplifier topologies. The FET's source terminal is the input, the drain is the output, and the gate is connected to ground (or "common", hence the name). It has a low input impedance and current gain near unity so it is typically used as a current buffer, or as part of a cascode amplifier (formed using a common source followed by a common gate amplifier), which takes advantage of the common source's high voltage gain while the common gate reduces the Miller effect on the common source and thus improves the overall amplifier's bandwidth. The analogous BJT circuit is the common base.

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Common Emitter not amplifying

I am trying to make a 27 MHz carrier wave transmitter from a crystal oscillator and a secondary amplifier. This is the complete circuit: simulate this circuit – Schematic created using CircuitLab The first part, left of C6 is a colpitts crystal…
Golaž
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Common Gate Level Shifter

I am in the need for a high-side load switch and came up with the following schematic. High-Side voltage levels and current vary between 5-12 V / 2 A max. The high-side PMOS (SI5509DC) is rated for 20 V V_DS and 12 V V_GS and up to 4A. A 10 V Zener…
Arne
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Differences between EPROM and EEPROM

I found one valuable Utmel blog which explains the three things: The internal chip can be erased by irradiating ultraviolet rays through the hole. The EPROM eraser is needed to complete the chip erasing operation. PROM is a programmable device. The…
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Common Gate Transimpedance Amplifier Transfer Function

I am trying to find the transfer function of the common gate transimpedance amplifier. The transfer function that I got is different than the one at the original publication even though it leads to the same DC gain. There is no derivation in the…
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Common gate amplifier with load connected to negative DC bias

What's the difference between the following two circuits? Note that the capacitors are DC blocking, and the FET is on. I understand that usually, the load is connected to ground. But what would happen if it was connected to the negative DC bias?…
Andres Riofrio
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Calculate the upper cutoff frequency of a common gate

JFET: I am trying to calculate the upper cut-off frequency of this circuit. Gain gave me 5, as it did in the teacher's solutions. But I'm applying the expression to the condensers and it's giving me negative values! The initial circuit is as follows…
Carmen González
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Common Gate For Power MOSFET

The common base configuration has been well documented for the BJT. Small signal analysis shows better high frequency capability than a common emitter for the same transistor. I have seen common gate used on JFETs at VHF where the low input…
Autistic
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Why would a common Gate MOSFET (instead of a resistor) reduce noise in a TIA?

simulate this circuit – Schematic created using CircuitLab I am reading a paper on TIA for optical receivers. On one of the improvements regarding the noise the writers replace the feedback resistor with a common gate MOSFET biased on the triode. I…
Atheros
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How does the current pass through FET when its gate is unbiased/grounded in AC analysis?

My first question is how does the drain voltage increase V(drain) when the source voltage V(source) is increased for the below common gate FET: And secondly and most importantly in AC analysis they short the gate and Vdd to ground. What confuses…
user16307
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Common gate with low input impedance

This is from my textbook talking about the advantages of a common gate amplifier. The author says that the common-gate stage is usually superior to that of the common-source stage for two reasons. However, what makes me confused is about the second…
emnha
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Where to apply input source to common gate configuration

I have learned from my teacher that the input of the common gate is applied at the source pin and the output voltage is probed from the drain pin, why not vice versa? Can I do that?
Got
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Convert boolean expression to nand gate only. X = A'B'C+AB'C'+A'B'

I have already made a diagram. However, it won't match the truth table that I have made, which I got from the logic converter in multisim. Could you please help me out with where did I go wrong? Is it on my diagram or in my truth table?
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Thevenin Equivalent of Common-Gate Amplifier

I'm having some difficulty understanding how Razavi determined \$V_{\text{in, eq}}\$. My understanding was that the small-signal model allows us to model the PMOS device as a constant current source (\$g_mv_{gs}\$) with a resistor in parallel…
AlfroJang80
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Small-signal voltage gain of P-type common-gate circuit

Given the following p-type common-gate circuit, I'd like to try and calculate the voltage gain \$A_v=V_o/V_i\$. Given the following information: \$V^+=5V\$, \$V^-=-5V\$,\$V_{TP}=-0.8V\$,\$\lambda=0\$, \$K_p=0.001mA/V^2\$ I began by doing a DC…
Blargian
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Find gain of this common-gate

I have a large circuit involving feedback as follows I am trying to find the closed-loop gain of this. Before I can do that, I need to find the open-loop gain. Thus, removing the feedback loop, M2 becomes useless and I am left with a common-gate…
AlfroJang80
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